Method for producing a photographic element

ABSTRACT

A METHOD FOR PRODUCING A USEFUL AND PRACTICAL PHOTOGRAPHIC ELEMENT HAVING EXCELLENT WATER-RESISTING PROPERTIES, DIMENSIONAL STABILITY AND RAPID-DRYING QUALITIES COMPRISING TREATING A BIAXIALLY-STRETCHED AND ROUGHED POLYSTYRENE FILM BASE WITH A CORONA DISCHARGE OR ELECTRON IRRADIATION, APPLYING, IF NECESSARY, A GELATIN LAYER TO SAID BASE, AND THEN APPLYING A GELATIN-CONTAINING PHOTOGRAPHIC EMULSION OR SUSPENSION ONTO THE TREATED SURFACE OF THE SUPPORT.

Get. 10, 1972 sUMlTAKA TATSUTA ETAL 3,597,305

METHOD FOR PRODUCING A PHOTOGRAPHIC ELEMENT Filed Dec. 8, 1970 FIG. I

FIG 2 INVENTORS SUMITAKA TATSUTA WATARU UENO TATSUYA TAJIMA MUTSUO AKAO sw knu 'KDHWJP m YXWA I WACPQQK ATTORNEYS United States Patent 3,697,305 Patented Oct. 10, 1972 US. Cl. 117-47 A 6 Claims ABSTRACT OF THE DISCLOSURE A method for producing a useful and practical photographic element having excellent water-resisting properties, dimensional stability and rapid-drying qualities comprising treating a biaxially-stretched and roughed polystyrene film base with a corona discharge or electron irradiation, applying, if necessary, a gelatin layer to said base, and then applying a gelatin-containing photographic emulsion or suspension onto the treated surface of the support.

BACKGROUND OF THE INVENTION Field of the invention The present invention relates to a method of producing a photographic element.

Description of the prior art Baryta paper has generally been used as a photographic support for photographic paper or as the element for a silver salt diffusion transfer process. Baryta paper is produced by applying an aqueous mixture of finely divided barium sulfate and a small quantity of binder such as gelatin on a paper made from pulp. The paper has various disadvantages such as its easy expansion and contraction depending upon moisture variation, especially, shrinkage after development, and its weakness to water.

The foregoing disadvantages can be overcome by using a support produced by dipping a polymer film, for example, a polystyrene film, in a solvent or swelling agent and then whitening the treated surface by dipping the film in a non-solvent for the polystyrene. The film has very desirable properties as a photographic supportdue to its superior water-resisting quality, drying velocity, dimensional stability, stiffness, opacity and the like.

Polystyrene has, however, the disadvantages as a support for photographic paper in that it is difficult to firmly bond a photographic emulsion layer containing hydrophilic gelatin thereto, due to the hydrophobic and chemically-inactive properties of poystyrene.

It is well known that a remarkable improvement in adhesion can easily be obtained by subjecting polyethylene or other film material consisting of hydrophobic polymers to a corona discharge treatment. In the case of polystyrene, however firm adhesion cannot be generally eifected even by treating the same with a corona discharge. When a 1-10% aqueous solution of gelatin is applied to a biaxially stretched polystyrene support subsequent to treatment with a corona discharge, the adhesion is so poor that the gelatin layer formed is released naturally from the surface of the support.

As a result of many studies directed toward overcoming the foregoing disadvantages of baryta paper, the present inventors attained the present invention.

An object of the present invention is to obtain a novel photographic paper having excellent Water-resistance, dimensional stability and a rapid drying property.

SUMMARY OF THE INVENTION The present invention provides a method for the production of a photographic element which comprises treating a biaxially stretched roughed polystyrene support with a corona discharge or electron irradiation and, if necessary, applying a gelatin layer thereto, and then applying a photographic emulsion or suspension containing gelatin as a binder, to the treated surface.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 represent suitable apparatus for conducting the corona discharge and electron irradiation treatments, respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The phrase r biaxially stretched roughed polystyrene film, as used herein, refers to a process consisting of biaxially stretching an extruded polystyrene film by a conventional prior art biaxially stretching method, contacting, for 0.5 to 30 seconds, the stretched film with organic solvents capable of dissolving or swelling the polystyrene, such as tetrahydrofuran, methyl acetate, ethyl acetate, acetone, methyl ethyl ketone, methylene chloride, ethylene chloride, cyclohexane, benzene or mixtures thereof to swell the film, then roughing by contacting, for more than one second, the surface of the film with organic solvents which are compatible with the organic solvents used in the swelling treatment but which do not dissolve the polystyrene, such as methanol or ethanol. The contacting of the polystyrene film with the solvents can usually be accompished by either dipping the film in the organic solvent, applying the organic solvent to the film by a roller applicator or a brush, or spraying the organic solvent onto the film. In general, the most eifective roughing process has been a mechanical abrasion or whitening of the whole film by the incorporation of a foaming agent such as a normal alkane capable of generating a gas upon heating rather than the above contacting process with an organic solvent.

The biaxial stretching of the film can be accomplished by stretching both axes of the film at the same time or separately for the purposes of the present invention. Any conventional prior art biaxial stretching process may be employed.

The polystyrene resin may also be used in combination with 5 to 40 weight percent of a White pigment such as, for example, titanium dioxide, barium sulfate, calcium sulfate, barium carbonate, lithopone, alumina white, calcium carbonate, silica white and the like, and, if necessary, a colored pigment. The Whitening or the opalizing of said film according to the foregoing process imparts a valid photographic scene to the photographic element produced from the treated support. The polystyrene resin has excellent water-resistance, dimensional stability, stiffness and other advantageous properties, and especially when the film is treated in the foregoing manner, it exhibts superior whiteness and opacity. It may be very desirable as a support for photographic elements. However, it is difiicult to bond the polystyrene resin to a hydrophilic gelatin-containing emulsion due to the hydrophobic and chemically inactive properties of the polystyrene as mentioned above.

The present invention overcomes these disadvantages in the treatment of the roughed polystyrene film with a corona discharge or with electron irradiation. According to our reliable studies, the present inventors have found that roughed polystyrene film, without being subjected to a corona discharge treatment or electron irradiation, has a contact angle to water of 90, that film treated with a corona discharge or electron irradiation according to the present invention results in decreased values of the contact angle of.5-6 and 35-50 respectively, and that said treatments make the surface of the polystyrene film remarkablyhydrophilic. Furthermore, test results demonstrate that, although in the case of a biaxially stretched non-roughed polystyrene film, the contact angle is decreased to to 50 bytreatment with a corona discharge orv electron irradiation, it is difiicult to effect a firm adhesion between the film and a coating of an emulsion consisting essentially of gelatin. When, however, the roughed, biaxially stretched polystyrene film is treated with a corona discharge or electron irradiation, the adhering strength between the film coating of the emulsion containing gelatin and the treated film surface is markedly greater in both the dry state and the wet state during development.

For example, even if the exfoliation at the boundary surfaces of the two phases between said film and said film coating are done in .the dry state, the adhesion between the two is so strong that the cohesive failure is in the internal film without releasing said film coating from said film. In this case, the cohesive failure strength is sufficient to provide the good adhering strength required between the film coating and the support, such as, the photographic emulsion layer or an image-receiving layer.

Furthermore, the adhering strength between the support and the film coating does not deteriorate even after standing for a long period of time.

The corona discharge treatment according to the present invention can be accomplished by utilizing the apparatus shown in FIG. 1.

Inw FIG. 1, 1 is avhigh frequency generator; 2 is an electrode; 3 is a treatment roller whose surface is coated with chlorosulfonated polyethylene (Hypalon) or with a polyester film; 4 is a ground; and 5 is the film base to be treated. The corona discharge treatment is carried out while the film base is travelling between 2 and 3. The voltage across the electrodes is usually from 5 kv. to 500 kv. but is not necessarily limited to this range. The electrode distance can be varied depending on the thickness of the film base to be treated, but a range between 0.5 mm. and 10 mm. is generallypreferred. The velocity of the film base is generally between 1 and 20 mm./min., but can be properly varied depending on thekind of apparatusv used and the treating eflect.

The electron irradiation may be conducted by utilizing the apparatus shown in FIG. 2.. In FIG. 2, 6 is a high voltage generator; 7 is an electron gun; 8 is an accelerator; 9 is ascanning coil; 10 is a vacuum pump; 11 is a scanning tube; and 12 is the film base to be treated. An elecing thereto silver halides such as silver chloride, silver.

chlorobromide and ,silver iodobromide; a photosensitive diazo compound; development nuclei of an image-receiving element used in a silver salt diffusion transfer process or various other components.

If necessary; a silver halide emulsion may be coated.

onto the gelatin emulsion layer so that the gelatin emulsion. layer is an undercoating layer for the silver halide emulsion.

In the present invention, the adherance of the aqueous gelatin layer film coating to the support is problematic, and it may not be-important whether any component is emulsified or suspended in the aqueous gelatin solution.

(1) DRY STATE ADHESION TEST A 0.14 mm. thick cellulose triacetate film was coated onto a specimen with an epoxy type adhesive and allowed to stand at 23 C. and at a relative humidity of 65%; then cut into a long strip-like shape, 1 cm. wide and 15 cm. long; thereafter, said film was released at a drawing velocity of 7.38 cm./min. The releasing strength was measured with a strain gauge. In the examples, the term good adhesion in test tested specimen refers to a releasing strength greater than 8 g./mm., which is satisfactory for a photographic element.

(2) WET STATE ADHESION TEST The same surface of the above specimen, after developing, fixing or water-washing, was bonded in a wet state, with a cyanoacrylate type adhesive, a cellulose triacetate film in the same manner as in (1) and the releasing strength was measured. In this case, good adhesion refers to a releasing strength greater than 2 g./mm., which is sufficient for a photographic element.

In the following examples, part is by weight.

EXAMPLE 1 A biaxially stretched 0.1 mm. thick polystyrene support was dipped in a solution consisting of 7 parts ethyl acetate and 1 part ethanol-for 3 seconds and then dipped in methanol for an additional 30 seconds to whiten and opalize the support. The roughed polystyrene support was subjected to a corona discharge treatment using a corona discharger (Model HFSG-l produced by Lepel High Frequency Laboratories) under the following conditions.

Distance between electrodes (mm.) 0.8 Length of electrode (mm.) 300 Thickness of electrode (mm.) 10 Frequency (mc.) l Feeding speed of support (rn./min.) 2 Discharging electric power (w.). 12-175 After the corona discharge and roughing treatments, the polystyrene support surface was coated with a gelatinsilver halide photographic emulsion having the following composition per 1 m. of film.

Silver chlorobromide (chlorine:bromine=3 molez7 mole) 3.5 Gelatin 13.0 Formalin (hardener) 0.1 Saponin 0.03

The adhesion between the emulsion layer and the film base, as confirmed by the releasing test results shown in the table below is large enough, such that 'it does not result in exfoliation at the boundary surface.

In the dry state, the releasing test leads to a cohesive failure at the internal film with a cohesive failure strength greater than 8 g./mm. which is satisfactory for a photographic element. 7

Further, in the wet state, the boundary surface between the emulsion layer and the support was not released; the

break occurred in the internal emulsion layer. The adhesion between the emulsion layer and the film base was greater than 2 g./mm. which is satisfactory for a photo- 6 graphic element, and furthermore the adhesion had not EXAMPLE 4 deteriorated even after standing for a long time.

On the other hand, when a roughed polystyrene support, A biaxially stretched 0.2 mm. thick polystyrene film which had not been subjected to a corona discharge treatbase was dipped in a solution consisting of 15 parts ethylment was coated with the emulsion in like manner as 6 Chloride, Parts ethanol d 1 Pa t Water for 3 above, the adhesion was extremely inferior in both the Seconds and then dipped in methanol for 30 seconds to dry and the wet states, and was below 2 g./mm. in the obtain a whitened and opalized film base with a porous dry tate and nearly 0 g/ m, in th w t tate layer on the surface. The roughed polystyrene support A transparent polystyrene film, which was treated with was subjected t0 a COIOHB. discharge treatment under the a corona discharge in like manner as above, but not 10 same conditions as in Example 1, and then a gelatin-silver roughened, was extremely inferior in its adhesion in both alide color photographic emulsion having the following the dry and the wet states with both releasing tests result- C mp siti n was applied thereto per 1 m. of film. ing in a release strength of 0 g./mm.

Discharge electric power (w.). 0 12 32 50 100 175 Dry state releasing 1.8 28.1 23.2 20.8 22.0 20.2 20.6.

strength (g.lmm.). Released position Emulsion layer/ At the internal At the internal At the internal At the internal At the internal At the internal support. support. support. support. support. support. support. Wet state releasing 0 4.0 3.8 4.6 5.2 4.1 4.8.

strength (g./mm.). Released position Emulsion layer] At the internal At the internal At the internal At the internal At the internal At the internal support. emulsion emulsion emulsion emulsion emulsion emulsion layer. layer. layer. layer. layer. layer.

1 Emulsion layer/support refers to the exfoliation at the boundary surface between the emulsion layer and the backing surface. At the internal support refers to the cohesive failure of the support.

EXAMPLEZ Silver chlorobromide (chlorine:bromine=3 mole:7 A biaxially stretched 021 mm. thick polystyrene supg: Z

port was dipped in a solution consisting of 1 part acetone and 1 part methyl ethyl ketone for 3 seconds and then dipped in methanol for seconds to obtain a whitened, 30 con er v 14 0 opalized support with a minute porous layer on the surg ""gfigggflgg gag6%";g; 5: face. The roughed polystyrene layer was subjected to a tion ml 3 0 corona discharge treatment under the same conditions as Emulsified dispersion containing benzoylaceto-Z- chloro-5-dodecyloxycarbonyl anilide as a yellow i Example 1, and thereafter was coated with the follow- Polyvmylpyrmhdone ing aqueous gelatin solution per 1 m? of said film. The releasing test of the film coated with said color Gelatin 10 photographic emulsion was performed, and the adhering Water 190 strength was found to be greater than 12 g./mm. in the dry state and greater than 4 g./mm. in the wet state. It

Formalm (20% aqueous solutwn) 4 exhibited an adhering strength which is satisfactory for a The gelatin-silver halide photographic emulsion as menphotographic elemehh tioned in Example 1 was applied to said gelatin layer. It o the other hand, the adhesion obtained b l i BXhihited a good adhesion Strength of greater thtln 20 g/ the gelatin-silver halide color photographic emulsion to Him in the y State and greater than 5 gJIIlIlL in the Wet said roughed film base without first subjecting the film state. On the ther a the adhesion Obtained by pp base to a corona discharge treatment, was extremely ing the foregoing gelatin solution to the roughed film base poor without the corona discharge treatment was inferior. EXAMPLE 5 EXAMPLE 3 A biaxially stretched 0.1 mm. thick polystyrene film was dipped in a solution consisting of 7 parts ethyl acetate and 1 part ethanol for 3 seconds and successively dipped in methanol for 30 seconds to whiten and opalize the film. The roughed film was then treated with electron irradiation under the following conditions by means of an electron accelerating apparatus (300 ev. transformer type electron accelerating apparatus manufactured by Nisshin Electric Works, Ltd.).

A biaxially stretched 0.2 mm. thick polystyrene support was dipped in a solution consisting of 1 part benzene and 1 part acetone for 2 seconds and then dipped in methanol for an additional 30 seconds to obtain a whitened, opalized film base with a porous layer on the surface. The roughed polystyrene support was subjected to a corona discharge treatment under the same condition as in Example 1 and thereafter was coated with a solution for an image-receiving layer, which was used in Voltage used kv 300 a silver salt diffusion transfer process, having the fol- Beam electric nt ma 25 lowing composition per l m? of said film. Dosage:

(1 M rad 1 Gelatin 3 M rad 2 Ag S colloid 0.001 M rad 4 Phenylmercaptotetrazole 0.01 M mi. 8 Sapomn The s l ing film was successively coated with a ilver The releasing test for the image-receiving material was halide Photographic emulsion having the following comperformed, and the adhesion was found to be 15 g./mm. Posltlon Per 1 111-2 of said in the dry state at a discharge electric power of 50 w., G.

and 5.0 g./mm. in the wet state. It exhibited an adhesive chlotobromlde 3.5

strength which is satisfactory for an image-receiving ma- Gelatm (blnder) 13.0

terial for a silver salt diffusion transfer process. Formqlm t 0.1 On the other hand, there was no adhesion obtai ed by (wemng ageht for g) 0.03

applying the coating solution for the image-receiving layer Flned up to 130 with Waterto the roughed film base without subjecting the film base The releasing test of the film coated with said emulsion to a corona discharge treatment. was performed and the releasing strength for all of the treating conditions was found to be greater than 10 g./mm. in the dry state and greater than 2 g./mm. in the wet state. The adhesion strength of said emulsion layer to said film base is satisfactory for a photographic element. Furthermore, these adhering strengths were not deteriorated even after standing for a long time.

On the other hand, when a roughed polystyrene support which had not been first treated with electron irradiation, was coated with saidemulsion, the adhesion was extremely poor in both the dry and the wet states, and the releasing strength was below 2 g./mm. in the dry state and nearly g./ mm. in the wet state. Furthermore, when a transparent polystyrene film, which has been treated with electron irradiation but not roughed, is coated with said emulsion, the adhesion was extremely inferior in both the dry and the wet states, with releasing strengths of 0 g./mm. for both states.

From the result of this example, it was confirmed that both the roughing and the electron irradiation treatment of the polystyrene film is substantially essential for imparting a releasing strength satisfactory for a photographicv element.

EXAMPLE 6 A biaxially stretched 0.1 mm. thick polystyrene film was dipped. in a solution consisting of 1 part of acetone and 1 part of methyl ethyl ketone for 3 seconds and successively dipped in methanol for seconds to obtain a whitened and opalized film. Said roughed polystyrene film base was treated with electron irradiation under the same conditions as in Example 5 and an aqueous gelatin solution having the following composition per 1 m? of said film was applied.

Gelatin (component for undercoat) g 10 Formalin (20% aqueous solution hardener) cc 4 Water g 190 EXAMPLE 7 A biaxially stretched 0.2 mm. thick polystyrene film was dipped in a solution consisting of 1 part of benzene and 1 part of acetone for 2 seconds and then dipped in methanol for 30 seconds to obtain a whitened and opalized film with a porous layer on the surface. Said roughed polystyrene film was treated with electron irradiation under the same conditions as in Example 5, and successively was coated with a solution for forming an image-receiving layer, which was used in a silver salt diflusing transfer process, having the following composition per 1 m? of said film.

G. Gelatinv (binder) 3 Silver sulfide colloid (developing nucleus) 0.001 Phenylmercaptotetrazole (color toning agent) 0.01 Saponin (wetting agent) 0.02

The releasing test for said image-receiving material was performed and confirmed to be satisfactory for an imagereceiving material for a silver salt difi using transfer process in both the dry and the, wet states.

'On the other hand, there was no adhesion obtained by applying the coating solution to said roughed film base for forming an image-receiving layer, without subjecting the film base to an electron-irradiation treatment.

8 EXAMPLE s A biaxially stretched 0.2 mm. thick polystyrene film was dipped in a solution consisting of 15 parts of ethylene chloride, 15 parts of ethanol and 1 part of water for 3 seconds and successively dipped in methanol for 30 seconds to obtain a whitened and opalized film with a porous layer on the surface. Said roughed polystyrene was treated with electron irradiation under the same conditions as in Example 5, and successively was coated with a silver halide color photographic emulsion having the following composition per 1 m? of said film.

Silver chlorobromide g 3.0 Gelatin g 3.5 Emulsified dispersion containing benzoylaceto-2- chloro-S-dodecyloxycarbonyl anilide (yellow coupler) g 14.0 Triethylene phosphamide (3 acetone solution) -ml 3.0 Polyvinylpyrrolidone g 0.7

jecting the resulting polystyrene support to the action of a corona discharge or electron irradiation and applying a gelatin-containing emulsion layer onto said support.

2. The method of claim 1 wherein said gelatin emulsion contains silver ion precipitants as physical-development nuclei.

3. The method of claim 1 wherein said roughing comprises treating said polystyrene support with a first organic solvent capable of swelling the polystrene and then treating said polystyrene support with a second organic solvent compatible with said first organic solvent but which does not swell the polystyrene.

4. The method of claim 3 wherein said first organic solvent is tetrahydrofuran, methyl acetate, ethyl acetate, acetone, methyl ethyl ketone, methylene chloride, ethylene chloride, cyclohexane, benzene or mixtures thereof.

5. The method of claim 3 wherein said second organic solvent is methanol or ethanol.

6. The method of claim 3 wherein said polystyrene support is first contacted with said first organic solvent for from 0.5 to 30 seconds and then contacted with said second organic solvent for a period of time of more than 1 second.

References Cited UNITED STATES PATENTS 3,311,497 3/1967 Park 96-47 A 3,146,883 9/1964 Harlan et al 11747 A FOREIGN PATENTS 893,436 4/1962 Great Britain 96-87 R RONALD H. SMITH, Primary Examiner US. Cl. X.R. 

